In recent years, batteries have been used for various purposes; and batteries with a large capacity in particular are used for power supply for electric vehicles, electric power storage, and so forth.
In a case where a single battery cell is used, a voltage of the battery cell may be lower than a voltage required by an electric device. In such a case, it is necessary to connect two or more battery cells in series in order to increase the supply voltage to a desired voltage. In another case, a single battery cell may not supply as much electric energy as required by an electric device. In such a case, it is necessary to connect two or more battery cells in parallel in order to increase the supply electric energy to a desired quantity.
For this reason, a battery box or an assembled battery in which two or more battery cells are connected in series or in parallel is provided; and power is supplied to the electric devices from these batteries. Some batteries such as batteries for mobile bodies and batteries for power storage in particular are required to have a high voltage and capacity, and these batteries are also required to have an easy-to-handle structure in such a way that any of single battery cells in the assembled batteries is replaceable. Therefore, the assembled batteries that meet these requirements are desired.
There are some well-known ways of connecting two or more battery cells in series or in parallel such as using a bus bar(s) between external terminals (see, for example, PTL 1), and welding a bended electrode terminal (see, for example, PTL 2). It has been also known that battery cells whose electrode terminal is bended in a battery pack (see, for example, PTL 3).